Re: [External] Re: [PATCH 2/4] kexec: add CONFING_KEXEC_PURGATORY_SKIP_SIG

From: 黄杰 <huangjie.albert@bytedance.com>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Eric Biederman <ebiederm@xmission.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Nick Desaulniers <ndesaulniers@google.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Michael Roth <michael.roth@amd.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Kuppuswamy Sathyanarayanan 
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Sean Christopherson <seanjc@google.com>,
	Joerg Roedel <jroedel@suse.de>,
	Mark Rutland <mark.rutland@arm.com>,
	Kees Cook <keescook@chromium.org>,
	linux-kernel@vger.kernel.org, kexec@lists.infradead.org,
	linux-kbuild@vger.kernel.org
Subject: Re: [External] Re: [PATCH 2/4] kexec: add CONFING_KEXEC_PURGATORY_SKIP_SIG
Date: Mon, 25 Jul 2022 21:32:59 +0800	[thread overview]
Message-ID: <CABKxMyOcePkvAvMyrG2r08yRuxx=gK2SnMBFbKzKW6hBAdmRFw@mail.gmail.com> (raw)
In-Reply-To: <Yt6JRBToqY5ts6OU@zx2c4.com>

maybe a boot parameter ?

Jason A. Donenfeld <Jason@zx2c4.com> 于2022年7月25日周一 20:15写道：
>
> Hi Albert,
>
> On Mon, Jul 25, 2022 at 04:38:54PM +0800, Albert Huang wrote:
> > +config KEXEC_PURGATORY_SKIP_SIG
> > +     bool "skip kexec purgatory signature verification"
> > +     depends on ARCH_HAS_KEXEC_PURGATORY
> > +     help
> > +       this options makes the kexec purgatory do  not signature verification
> > +       which would get hundreds of milliseconds saved during kexec boot. If we can
> > +       confirm that the data of each segment loaded by kexec will not change we may
> > +       enable this option
> > +
>
> Some grammar nits here, but actually, wouldn't it be better to make this
> depend on some other signature things instead? Like if the parent kernel
> actually did a big signature computation, then maybe the purgatory step
> is needed, but if it didn't bother, then maybe you can skip it. This
> way, you don't need a compile-time option that might change some aspect
> of signature verification people might otherwise be relying on.
>
> Jason